Automatic ground-detector for electric circuits



(No Model.)

0. P. LOOMIS. AUTOMATIC GROUND DETECTOR FOR ELECTRIC CIRCUITS.

No. 396,582. Patented Jan. 22, 1889.

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UNITED STATES PATENT OSBORN P. LOQMIS, OE SOIIERYILLE, MASSAtlll SE'lTS, AHSIGNOR TO THE LOOMIS ELECTRIC MANUEAUFIIRING COMPANY, Oi NEIV YORK.

AUTOMATIC GROUND-DETECTOR FOR ELECTFilC CiRCUlTS SPECIFICATION forming part of Letters Patent No. 396,582, dated January 22, 1889.

Applic i filed August 7, 1888. Serial No. 282,182. (No inotlelm T 0 all whom, it may concern.-

Be it known that I, OsBoRN I. IA'H'JMIS, a citizen of the "United States, residing at Somerville, in the county of Middlescx and State of Massachusetts, have invented a certain new and useful Automatic (,irouinl-Detector for Electric Circuits, of which the following is such a full, clear, and exactdescription as will enable anyone skilled in the art to which 3 it appertains to make and use the same, reterence being had to the accompanying drawings, forming part of this specification.

My invention relates more nirticularly to grounddetectcns for electric-light circuits.

The object of the invention is to indicate when an electric circuit becomes grounded at i any point or any portion of the current shortcircuited.

The invention consists in a ground-wire connected, at preferably the central station, to a wire in electrical communication between l the two parts of the circuit, in wh ch groundwire, or in the connection between the two parts of the circuit, or in both, may be placed one or more devices to indicate when a por- 1 tion of the current is passing over the ground wire, which would occur only when the cir ing device, and Fig. III shows a portion of i the apparatus of Fig. I with the lamp 12 ot the signal device in the ground-wire omitted.

The same figures of reference indicate corresponding parts throughout the several views.

Having now more particular reference to Fig. I, 1 designates a dynamo-machine supplying mains 2 and 3 with current, and l 5 and i 6 7 are subsidiary or house circuits connected with the aforesaid main by having incandescent lamps arranged in multiple are between the same.

My invention is not confined to use with an electrical-lighting circuit nor to an incandescent elect-ricdighting circuit, as are lamps or any other translating devices can be supplied l'roln the main 2 and I in any wellknown manner. g 8 is a wire connected from one main to the 1 other, and is providtai with suitable resisl tances, in order to prevent too great a portion 1 of the current from passing over said wire and short-circuiting the machine. I preferably arrange in said wire 8 two incandescent lamps, 9 and 10, in series therein, and connect the ground-wire 'ii at a point intermediate between the two lamps. In this grouml-wire l I arrange, preferably, a third incandescent j lamp having a colored globe.

13 indicates a gas or water npe, with which apart of the circuit may come in contact, and thus short-circuit a portion of the cur- I rent should the insulation of the circuit be imperfect at said point. The ground may be formed by any part of the circuit touching iany conductor in communication with the ground, such, for instance. as the roof of a building. 'hen this occurs, the current will 1 be short-circuited to ground, and by way of the ground back to the opposite terminal of the dynamo, the insulation of which is always more or less imperfect. In the prescntinvention, however, the current would pass from l the ground to the groundwvire it by way of the lamp l2, and through one oi? the lamps 9 i or lOback to the other-terminal oi the dynamo. Thus the colored lamp at the central oilicc would become lighted, and the nttent'iant in 1 charge would at once be made aware of the I fact that a ground had occurred at some point of the circuit. This willoccur when the mains f themselves establish the groulid-connection, or when any part of the subsidiary circuits i form a ground. The lamp 12, which normally ilS extinguished, will in either case become ll lighted and give the warning. l

In Fig. II the operation is precisely the j same, except that an electric bell. l-l, is used in place of the lamp 12. This bell preferibly made in a well-knmvn way, so as to cut in and out the magnet-resistance only as the bell vibrates, so that the circuit will always remain intactand there willbe no sparking. as ;there would. be in the case of an absolute make-and break ot' circuit in the ordinary i rheotome-bell.

In Fig. III the ground-wire 11v is not provided with an indicator-lamp, such as 12. In this-instance when the ground is established one of the lamps 9 and 10 would burn with greater brillian cy than the other, and thus inform the attendant that something wrong with the circuit, for under normal operations both lamps 9 and 10 burn with equal candlepower, being arranged in series in the same circuit 8, as before described.

In the apparatus shown in Fig. I the same function would be performed by the lamps 9 and 10. The colored lamp 12 is provided in order to render the signal more conspicuous. In place of the incandescent lamps shown in Figs. I and II, resistance-coils could be used as well or any other electrical deiices with sufficient resistance.

I do not wish to limit myself to any kind of an indicating device, as any suitable signalgiving device could be used; nor do I wish to be confined to the exact arrangement and location of the parts described, as the same may be varied by those skilled in the art without departing from my invention.

\Vhat I desire to claim, and secure by Letters Patent of the United States, is

An automatic ground-detector for electriclight circuits, consisting of a wire, 8, connected, preferably, between the mains of said circuit at the central station, electric lamps 9 and 10 in series in said circuit 8, a ground-connection between the two, for the purpose described, and a signal-giving device located in said ground, substantially as and for the purpose described.

In testimony whereof I have hereunto set my hand, this 1st day of August, 1888, in the presence of two subscribing witnesses.

OSBORN P. LOOMIS. [L. s] 'Witnesses:

GEo. WYATT DICKERMAN, W. A. WARNER. 

